In wirefree communications systems, a distinction is normally drawn between fixed stations and mobile stations, in which case two or more mobile stations can communicate with one fixed station. In recent years, a range of standardized modulation methods, such as DECT, WDCT, Bluetooth, GSM or 3GPP have become established in the field of mobile radio technology. Transmission data, such as speech, text or image data, is modulated by means of modulators onto a carrier frequency in the transmitting devices in the fixed stations and in the mobile stations. These modulators are generally formed from different functional units. Normally, they are split into a baseband part and a radio frequency part.
Within the baseband part, a baseband signal is produced from the data to be transmitted, by means of digital signal processing. This relatively low-frequency baseband signal is shifted to radio frequency within the radio frequency part. This shifting process is carried out, by way of example, using a homodyne or heterodyne transmission architecture. The data to be transmitted is then sent, after power amplification, by means of an antenna via a radio channel. The data is received in a corresponding manner, first of all via the radio frequency part, in which the original baseband signal is reproduced from the radio frequency signal, and then via the baseband part, in order to obtain the data to be transmitted.
Owing to the different physical requirement, the baseband and radio frequency parts are generally produced using integrated circuits (semiconductor chips) which are separate from one another. This subdivision is also necessary, in particular, as a result of the different power and frequency requirement. One already known example of such semiconductor chips is the DECT PMB 6720 baseband chip, and the DECT PMB 6610 radio frequency chip, from Infineon Technologies AG. The baseband chip and the radio frequency chip are connected to one another via a large number of lines in order to transmit the baseband signal and a range of control signals. A large number of connecting pins are therefore required on both semiconductor chips. In contrast, a small number of connecting pins allows a simplified circuit layout. The production of both the semiconductor chips and of a circuit board in which the two semiconductor chips are connected to one another can thus be simplified, with its cost being reduced. A small number of connecting pins furthermore leads to a reduced contact area, once again allowing a simple housing choice for the baseband and radio frequency part, and thus a lower-cost system solution for the transmitting and receiving arrangement.